diff --git a/acorn.js b/acorn.js
index 1e8fc48b37..692e6c6796 100644
--- a/acorn.js
+++ b/acorn.js
@@ -805,7 +805,10 @@
 
   function readToken_pipe_amp(code) { // '|&'
     var next = input.charCodeAt(tokPos + 1);
-    if (next === code) return finishOp(code === 124 ? _logicalOR : _logicalAND, 2);
+    if (next === code) {
+      if (options.playground && input.charCodeAt(tokPos + 2) === 61) return finishOp(_assign, 3);
+      return finishOp(code === 124 ? _logicalOR : _logicalAND, 2);
+    }
     if (next === 61) return finishOp(_assign, 2);
     return finishOp(code === 124 ? _bitwiseOR : _bitwiseAND, 1);
   }
diff --git a/test/tests-6to5-playground.js b/test/tests-6to5-playground.js
index d0d5b0af8a..d04f037aaf 100644
--- a/test/tests-6to5-playground.js
+++ b/test/tests-6to5-playground.js
@@ -245,6 +245,83 @@ test("obj.x ?= 2;", {
   playground: true
 });
 
+
+
+test("x ||= 2;", {
+  type: "Program",
+  start: 0,
+  end: 8,
+  body: [{
+    type: "ExpressionStatement",
+    start: 0,
+    end: 8,
+    expression: {
+      type: "AssignmentExpression",
+      start: 0,
+      end: 7,
+      left: {
+        type: "Identifier",
+        start: 0,
+        end: 1
+      },
+      right: {
+        type: "Literal",
+        start: 6,
+        end: 7,
+        value: 2,
+        raw: "2"
+      },
+      operator: "||="
+    }
+  }]
+}, {
+  playground: true
+});
+
+test("obj.x ||= 2;", {
+  type: "Program",
+  start: 0,
+  end: 12,
+  body: [{
+    type: "ExpressionStatement",
+    start: 0,
+    end: 12,
+    expression: {
+      type: "AssignmentExpression",
+      start: 0,
+      end: 11,
+      left: {
+        type: "MemberExpression",
+        start: 0,
+        end: 5,
+        object: {
+          type: "Identifier",
+          start: 0,
+          end: 3,
+          name: "obj"
+        },
+        property: {
+          type: "Identifier",
+          start: 4,
+          end: 5,
+          name: "x"
+        },
+        computed: false
+      },
+      right: {
+        type: "Literal",
+        start: 10,
+        end: 11,
+        value: 2,
+        raw: "2"
+      },
+      operator: "||="
+    }
+  }]
+}, {
+  playground: true
+});
+
 // Method binding
 
 test("var fn = obj#method", {